基于COSMIC掩星观测的中国内陆Es分布统计研究

我们采用COSMIC掩星系统提供的2009年1月1日至2010年12月31日的GPS信号信噪比（signal-to-noise ratio，SNR）的观测数据，通过计算SNR数据的归一化标准差对80~130 km高度范围内的中国内陆偶发E层（Sporadic E，Es）的空间分布以及垂直厚度等特性进行分析研究，获得了Es发生率的空间分布以及发生率随着季节的变化特征.中国内陆30°N纬线以上区域Es分布随季节变化较为明显，夏季最多，秋季次之，春冬季最少，而南部低纬地区发生率水平常年较高.一般情况下Es主要存在于90~110 km高度范围内，但在夏季100 km高度以下探测到了较多的Es事件，且主要表现为多层Es结构，可能是由大气重力波引起Es下行运动所致.Es厚度的分布统计表明：大结构Es的厚度分布在2.5~3 km范围内存在峰值，小结构Es厚度分布峰值出现在150~200 m范围内.

Statistical research of Es distribution in inland areas of China based on COSMIC occultation observations

We use the signal-to-noise ratio(SNR) data provided by the COSMIC occultation to analyze the distribution of Sporadic E(Es) in inland areas of China.The spatial and vertical thickness distributions of Es in the altitude range of 80~130 km are analyzed by using the normalized standard deviation of SNR data from January 1, 2009 to December 31, 2010. Then we get the seasonal and spatial distributions of Es occurrence rate derived from the normalized standard deviation.The occurrence rate of Es at latitudes of >30°N changes significantly with seasons:there is higher occurrence rate in summer,less in autumn,but lowest in spring or winter,while the occurrence rate is perennial high in the low latitude region of China. In general, the Es layers exist mostly between 90 km and 110 km in the E region.However,many events are detected below 100 km in summer, most of them belong to multiple layer structure, which may be attributed to descent of sporadic E layers caused by the atmospheric gravity waves. In addition, the thickness distribution of large scale Es has its maximum between 2.5 km and 3 km,and small scale Es has its maximum between 150 m and 200 m.